Conical Sunshading
Background
Currently, climate risk mitigation is largely pursued through emissions reduction pathways, supported by climate model projections that estimate future temperature outcomes, rather than through direct modification of Earth’s radiative balance. Within the broader discussion on geoengineering, sunshading has been proposed as a potential approach to reduce incoming solar flux and offset greenhouse-gas-induced warming. Climate modelling studies suggest that a reduction in total solar insolation of approximately ~1–2% could counteract the radiative forcing associated with a doubling of atmospheric CO₂ [1]. In space-based implementations, sunshading could be achieved by deploying large-scale structures or swarm systems near the Sun–Earth L1 point, enabling partial attenuation of solar flux before it reaches Earth.
Project goal
The goal of this project is to investigate the feasibility and performance of alternative sunshade geometries, beyond the conventional disk-shaped design proposed in the literature. Since the overall mass of the structure must remain above a minimum threshold [1], optimizing both geometry and optical properties is a key strategy for reducing overall system requirements. In particular, a promising concept is the conical sunshade: by employing inclined surfaces rather than a single flat reflector, the resulting redistribution of solar radiation pressure reduces the mass needed to achieve a given level of solar flux attenuation.
In addition, the project will also assess candidate materials, as well as feasible launch and deployment strategies. Special attention will be given to concepts based on ultra-thin, highly reflective films spanning very large areas, which must remain efficiently deployable and manufacturable at scale. To this end, we will investigate packing and deploying of large cones via origami folding and unfolding. Patterns for flat folding cones, for example via a Miura-Ori pattern [2], are known. We will investigate the mission specific origami parameters to minimize number of launches and additional deployment structure required, for example via automatic unfolding by centrifugal force.
References
- C. McInnes, Space-based geoengineering: Challenges and requirements, Journal of Mechanical Engineering Science Journal of Mechanical Engineering Science 224 (2010) 571–580.
- H. Sharma, S. H. Upadhyay, Folding pattern design and deformation behavior of origami based conical structures, Advances in Space Research 67 (7) (2021) 2058–2076